The present invention relates to nanoengineered sculptured thin films, and more particularly to nanoengineered sculptured thin films suitable for biological uses. Various references in the prior art have discussed the formation of sculptured thin films. Among these are U.S. Pat. No. 5,866,204 to Robbie et al. and U.S. Pat. No. 6,248,422 also to Robbie et al., which refer to sculptured thin film as sculpted thin film [1,2] and a corresponding publication [3]. To be clear, sculpted thin film refers to deposited films deposited in a manner to simulate a geometric form. Earlier works illustrate that as early as 1959 it was known to provide a substrate which is (i) inclined at a fixed angle about an axis parallel to the substrate plane; and (ii) which rotates about an axis passing normally 20 through the substrate plane during a deposition process. Young and Kowal disclose such a method [4]. Such a method is also disclosed by Dawson and Young [5]. In addition, work such as the 1989 paper by Motohiro and Taga contains SEM images of the resulting change in the geometry of a microstructure, including V-shaped columns [6].
References such as U.S. Pat. No. 5,866,204 to Robbie et al. and U.S. Pat. No. 6,248,422 also to Robbie et al. recognize the possibility of biocompatible sculptured thin film and potential uses [1,2]. In other work, various biocompatible substrates have been grown in micro and nanoscales and they have been used to control cell adhesion [7-10]. It is known that the topography of the surface alters proliferation, [11-13] and differentiation [14-16]. It has been also shown that submicron-scale features activate macrophage cell 30 adhesion and regulate the amount of F-actin in cells [17]. Recent research by Karuri et al. has shown that cell attachment on silicon columnar films can be dependent on nanoscale topography [18]: nanostructured surfaces affect cell morphology of human corneal epithelial cells. However, the long-term degradation of silicon interacting with biofluids is problematic, and the structures made heretofore require complicated and expensive techniques (e.g., lithography and masking). Alternative biological bottom-up technologies employ natural and artificial biopolymers such as collagen as bioactive surfaces. However, elevated medically significant environmental factors (e.g., temperature, pH, contaminants, and sterilizing agents and detergents) degrade biopolymers. Therefore, despite various advances made problems remain.
It should be appreciated that of the many advances in medicine during the last two decades, the engineering of implantable artificial organs and prosthetic devices is very exciting. Implantability requires that the device be biocompatible at least, and achieving bioactivity would be even better. Biological cells have been grown on nanostructured surfaces, which suggest the significance of nanomorphology for all surfaces of an implanted device that are going to be in contact with biological tissue. There is a growing realization that ongoing research in the areas of fundamental surface biology, nanofabrication, and recombinant DNA technologies will provide enhanced 3-dimensional tissues designed to accomplish specific biological and medical goals.
Imagine making a tissue sheet that can act as a filter in a kidney dialysis machine. Imagine a tissue sheet functioning inside a living heart as a tricuspid valve to regulate blood flow between an auricle and ventricle. Imagine a tissue sheet that will promote bone growth around a total knee replacement by ensuring that certain types of cells proliferate in comparison with others. What is needed is a biocompatible and bioactive material and methods of using the material in medical or other biological applications. As used herein, the term “bioactive” generally refers to components that bind to tissue. The term “biocompatible” refers to materials which are acceptable for at least some biological applications, and in particular may be compatible with tissue.